Pokémon Heroes was the fifth and final theatrically-released Pokémon movie, and thus the last one on this list. While not as bad as the first three, it's an extremely forgettable movie. It's a good thing I jotted down some notes immediately after watching it, because I did actually later forget completely what it was about. 

Ash & Co. travel to a city loosely inspired by Venice, Italy. Once upon a time in this city, there was an evil Pokémon trainer trained his Pokémon to attack humans, for the lulz. Then a guardian Pokémon entered the city and defeated them, but died in the process. However, before he died he managed to create a defensive weapon for the city that would be powered by his soul in crystal form -- because he was planning ahead -- which is protected by his two younger Pokémon children. Meanwhile, the two evil Pokémon have been fossilized and put on display in the same building as the weapon.

It turns out one of these guardian Pokémon children can take human girl form, because.

Two alternate members of Team Rocket going by the names Annie and Oakley are searching for these two guardian Pokémon children in order to capture them. They make the mistake of trying to catch the one while its in human form, just as Ash wanders by. Ash doesn't realize she's a Pokémon, and hilarious misunderstandings ensue.

Initially, Annie and Oakley just want to capture the two rare Pokémon. But after eventually defeating them, they suddenly decide that what they really want is the aforementioned soul crystal, and completely forget about the Pokémon. But after capturing the soul crystal, they suddenly decide that what they really want is to try out this defensive weapon, which incidentally might destroy the crystal when used. They don't seem clear on what they want to use the weapon for once they've activated it, it's just there and thus they need to play with it.

It turns out the weapon is able to revive the two evil Pokémon that once terrorized the city, turning them evil undead ghost Pokémon, which are then used to terrorize Ash &Co. But despite my colorful summary of the plot, the entire movie is actually extremely boring. I mean, so boring that it could function as a sleep aid. If you watch this on a lazy Sunday, you will fall asleep. Even the regular Team Rocket crew don't do anything interesting in this one.